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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2011 Gael Guennebaud <gael.guennebaud (at) inria.fr>
      5 //
      6 // This Source Code Form is subject to the terms of the Mozilla
      7 // Public License v. 2.0. If a copy of the MPL was not distributed
      8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9 
     10 #include "common.h"
     11 #include <Eigen/Eigenvalues>
     12 
     13 // computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges
     14 EIGEN_LAPACK_FUNC(syev,(char *jobz, char *uplo, int* n, Scalar* a, int *lda, Scalar* w, Scalar* /*work*/, int* lwork, int *info))
     15 {
     16   // TODO exploit the work buffer
     17   bool query_size = *lwork==-1;
     18 
     19   *info = 0;
     20         if(*jobz!='N' && *jobz!='V')                    *info = -1;
     21   else  if(UPLO(*uplo)==INVALID)                        *info = -2;
     22   else  if(*n<0)                                        *info = -3;
     23   else  if(*lda<std::max(1,*n))                         *info = -5;
     24   else  if((!query_size) && *lwork<std::max(1,3**n-1))  *info = -8;
     25 
     26 //   if(*info==0)
     27 //   {
     28 //     int nb = ILAENV( 1, 'SSYTRD', UPLO, N, -1, -1, -1 )
     29 //          LWKOPT = MAX( 1, ( NB+2 )*N )
     30 //          WORK( 1 ) = LWKOPT
     31 // *
     32 //          IF( LWORK.LT.MAX( 1, 3*N-1 ) .AND. .NOT.LQUERY )
     33 //      $      INFO = -8
     34 //       END IF
     35 // *
     36 //       IF( INFO.NE.0 ) THEN
     37 //          CALL XERBLA( 'SSYEV ', -INFO )
     38 //          RETURN
     39 //       ELSE IF( LQUERY ) THEN
     40 //          RETURN
     41 //       END IF
     42 
     43   if(*info!=0)
     44   {
     45     int e = -*info;
     46     return xerbla_(SCALAR_SUFFIX_UP"SYEV ", &e, 6);
     47   }
     48 
     49   if(query_size)
     50   {
     51     *lwork = 0;
     52     return 0;
     53   }
     54 
     55   if(*n==0)
     56     return 0;
     57 
     58   PlainMatrixType mat(*n,*n);
     59   if(UPLO(*uplo)==UP) mat = matrix(a,*n,*n,*lda).adjoint();
     60   else                mat = matrix(a,*n,*n,*lda);
     61 
     62   bool computeVectors = *jobz=='V' || *jobz=='v';
     63   SelfAdjointEigenSolver<PlainMatrixType> eig(mat,computeVectors?ComputeEigenvectors:EigenvaluesOnly);
     64 
     65   if(eig.info()==NoConvergence)
     66   {
     67     vector(w,*n).setZero();
     68     if(computeVectors)
     69       matrix(a,*n,*n,*lda).setIdentity();
     70     //*info = 1;
     71     return 0;
     72   }
     73 
     74   vector(w,*n) = eig.eigenvalues();
     75   if(computeVectors)
     76     matrix(a,*n,*n,*lda) = eig.eigenvectors();
     77 
     78   return 0;
     79 }
     80